$9qr + 9qs - 6q + 3 = -7r - 5$ Solve for $q$.
Combine constant terms on the right. $9qr + 9qs - 6q + {3} = -7r - {5}$ $9qr + 9qs - 6q = -7r - {8}$ Notice that all the terms on the left-hand side of the equation have $q$ in them. $9{q}r + 9{q}s - 6{q} = -7r - 8$ Factor out the $q$ ${q} \cdot \left( 9r + 9s - 6 \right) = -7r - 8$ Isolate the $q$ $q \cdot \left( {9r + 9s - 6} \right) = -7r - 8$ $q = \dfrac{ -7r - 8 }{ {9r + 9s - 6} }$ We can simplify this by multiplying the top and bottom by $-1$. $q= \dfrac{7r + 8}{-9r - 9s + 6}$